Tangeite Locality: Manganese Mine, Copper Harbor, Keweenaw Co., Michigan, USA Original description: Collected 2011 by D. Maietta. Field of view is 0.73 mm horizontal. Lens: Lens: Nikon M Plan 20 F-stop: N/A Mounting: Normal, extension = 210 mm FOV: 0.73 mm Lighting: Dual fiber partially diffused Processing: CombineZP do-stack retouched with manual stack composition — Photo: David M. Maietta · CC BY 3.0
Tangeite
A calcium-copper vanadate — 'calciovolborthite' — a secondary mineral of vanadium-bearing sandstones.
Intro adapted from Wikipedia (CC BY-SA).
Tangeite is an IMA-recognized mineral species in the vanadate class, with the chemical formula CaCu(VO₄)(OH).
It crystallizes in the orthorhombic crystal system (space group P2_12_12_1). It is a member of the Adelite structural group.
Key properties: Mohs hardness 3.5; specific gravity 3.75; Vitreous, pearly on the cleavage luster; refractive index 2.05; optically biaxial.
IMA symbol Tg, IMA status: approved, named in 1926.
Found as a rare secondary mineral in vanadium-bearing mineral deposits in sandstone.
It is found associated with Calcite, barite, malachite (Tyuya-Muyun, Kyrgyzstan); rhodonite, quartz, pyrobelonite, chalcocite, neotocite, copper (Molinello mine, Italy); malachite.
The name refers to its initially noted occurrence in the Tange Gorge, Fergana Valley, Alai Range, Kyrgyzstan.